[Parser] Handle #pragma pack/align inside C structs.

Fixes PR13580. Patch by Serge Pavlov!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179743 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 47826aa..a39cebc 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -3230,6 +3230,16 @@
       continue;
     }
 
+    if (Tok.is(tok::annot_pragma_pack)) {
+      HandlePragmaPack();
+      continue;
+    }
+
+    if (Tok.is(tok::annot_pragma_align)) {
+      HandlePragmaAlign();
+      continue;
+    }
+
     if (!Tok.is(tok::at)) {
       struct CFieldCallback : FieldCallback {
         Parser &P;